The present invention relates to a roll, and in particular, to a roll for a web like material.
Most commonly, rolls that can be bent have been formed so that they have a continuous axle and a roll mantle composed of a number of parts fitted on the axle. The roll can be curved in the desired shape by shifting the outermost journalling points of the roll mantle in the radial direction, in which case the mantle forms an arc or a broken line. The parts of the mantle have as a rule, been mounted on the axle each of them separately, in which case the arrangement comprises a number of bearings. The conventional solutions often involve problems, which include, among other things, bearing problems in the roll and heat peaks produced by the bearings in the paper web. A roll mantle composed of a number of parts may also form a considerable problem, because the gaps between the parts may mark the paper web and because the shape of the arc of the roll is not optimal, but the shape line of the roll is shaped as a broken line. Further, owing to the metallic roll mantle, problems of corrosion may arise.
The roll described in the applicant""s FI Utility Model No. 2788 comprises a non-revolving roll axle and a roll mantle mounted on the axle revolving by means of bearings. The roll mantle is a continuous tubular mantle, and the roll axle consists of three parts linked with each other. The inner ends of the two end parts of the roll axle, which are hollow in the interior, extend a certain distance into the interior of the hollow tubular middle part of the axle. In the end areas of the roll, support sleeves have been fitted, onto which sleeves the roll mantle itself has been mounted. The roll mantle has been mounted on each of the end parts of the axle by the intermediate of said support sleeves by means of two bearings placed at an axial distance from one another. The end parts of the axle have been connected with the middle part of the axle by means of articulated members so that the end parts of the axle can be inclined in relation to the middle part of the axle. The inclining takes place so that the end parts of the axle move in relation to the middle part of the axle in the radial direction. The roll bending mechanism comprises a cam member which forms a lever with two arms and which has been mounted pivotally on the wall of the tubular end part. The inner end of the cam member extends through the wall of said tubular end part to outside the end part and is supported against the inner face of the middle part. In the interior of the tubular end part, an axially displaceable regulation rod has been fitted, whose inner end is supported against the cam member. When the cam member is shifted in the axial direction, the cam member can be pivoted so that it is supported with a greater force against the inner face of the middle part of the axle while, at the same time, increasing the distance between the end part and the middle part of the axle at the side of the cam member, in which case the axle is bent. The roll mantle can be made of steel or of a composite material.
The solution described in said FI Utility Model No. 2788 is in itself operative, but it is relatively complicated and expensive.
The roll described in the applicant""s FI Patent Application No. 970379 is composed of two end parts and of a middle part. In this solution, the roll has no separate axle with a mantle revolving on said axle, but the middle part also operates as the axle of the roll, which is mounted on its support members by means of end bearings. The extensions of the middle part which operates as the axle have diameters substantially smaller than the diameter of the middle part, and their size corresponds to the diameter of an ordinary non-revolving axle. The end parts of the roll are tubular pieces, and they have been mounted directly on extensions of the middle part so that, at the inner ends of the end parts, articulation means have been fitted in the interior of the tubular end parts. The tubular end parts have been supported in the axial direction, in the area of their outer ends, by means of bearings, which have been fitted on support parts separate from the revolving parts. The support parts comprise sleeve-like pieces, whose inner diameter is larger that the diameter of the extension of the middle part, so that the positions of the bearings can be regulated radially. When the positions of the bearings of the tubular end parts are regulated, it is possible to regulate both the extent of curve form of the roll and the direction of the curve form. As the material of the mantle of this roll, it is also possible to use a composite material.
In said FI Patent Application No. 970379, an axle is used that extends through the roll mantle, and the whole of the construction of the roll is relatively complex, so that the cost of the roll becomes high.
In the FI Patent Application No. 951288, a roll is described that is provided with a continuous roll mantle or with a roll mantle composed of a number of parts. The material of the roll mantle is reinforced plastic or a similar composite construction. The roll is provided with a continuous support axle extending across the whole roll mantle, which axle is not rotated and which is supported in its place. In the middle portion of the support axle there is a thicker portion, on which the middle bearings of the roll have been mounted. Said bearings are supported on annular fitting pieces, by whose means the outer race of the bearing is supported on the roll mantle. At the ends of the roll, sleeves have been installed so that the sleeves extend a certain distance into the interior of the roll mantle and a certain distance to outside the roll mantle. The ends of the roll mantle have been journalled on said sleeves. Onto the sleeves, in the portion outside the roll mantle, regulation screws have been mounted, by whose means the sleeve can be diverted from the centre line formed by the support axle. When the sleeves are diverted from the centre line formed by the support axle, at the same time the centres of the outermost bearings of the roll are diverted from said centre line, in which case the roll mantle is bent, but the support axle remains straight all the time.
In said FI Patent Application No. 951288, a continuous support axle is used which extends through the whole roll mantle and in whose middle part there is a thicker portion. Thus, the roll becomes relatively expensive and heavy. Further, the roll has bearings also in the middle portion of the roll at the thicker portion of the support axle. These bearings fitted in the middle part of the roll cause said problems of heat in the roll mantle, and attempts have been made to reduce said problems of heat by means of annular fitting pieces installed between the outer races of the bearings and the inner face of the roll mantle.
In the EP Patent Application No. 363,887, a roll made of a composite material has been described. The invention of said EP patent application concerns the structures and materials of different surface layers of the roll mantle. FIG. 4 illustrates a revolving roll manufactured in accordance with the invention and meant for very high speeds, which roll is provided with a roll mantle of a composite material and with axle journals at the ends of the roll mantle. The axle journals are connected with the roll mantle by means of end flanges. Said EP patent application is expressly concerned with the material structure of the roll mantle, the object being to manufacture a roll of sufficient surface hardness, low weight, and high dimensional precision. The application does not mention bending of the roll.
Owing to its numerous advantageous properties, a composite roll is highly interesting. The roll solutions mentioned above, in which a roll mantle made of a composite material can also be employed, are, however, clumsy and expensive. Owing to the favourable material properties of a composite roll, such as modulus of elasticity and density, a composite roll can be dimensioned so that it can be bent to the desired curve form with a reasonable torque and that it operates either at a speed below the critical speed, i.e. below the lowest resonance frequency, or between resonance frequencies. If a steel roll is supposed to be bent to a required curve form without increasing the strains excessively, the roll diameter must be very small. In such a case, one or several critical speeds of the roll must be surpassed unavoidably.
With a steel roll, the bending torque required by the bending is also considerably higher than with a composite roll, in which case the bearing forces at a steel roll are also considerably higher than with a composite roll.
The solution in accordance with the present invention constitutes a substantial improvement over the prior-art rolls that can be bent.
In the roll in accordance with the present invention, there is a continuous tubular roll mantle of a composite material. At both ends of the roll mantle there are axle journals, by whose means the roll is attached to the frame of the machine. Thus, the roll has no axle passing through the roll at all. As compared with traditional spreader rolls, the construction of the roll in accordance with the present invention is clearly simpler, and its need of maintenance is little. The simple construction makes the manufacture of the roll easy and of low cost. Also, the simple construction facilitates servicing of the roll.